One-step microwave-assisted polyol synthesis of green luminescent carbon dots as optical nanoprobes

A one-step microwave-assisted polyol method was developed to fabricate green luminescent carbon dots (CDs). By using sucrose as the carbon source and diethylene glycol (DEG) as the reaction medium, the CDs were obtained within one minute under microwave irradiation. The as-prepared DEG stabilized CDs (DEG-CDs) had an average diameter about 5 nm and could be readily dispersed in water with transparent appearance in day light while emitted unique green luminescence upon a 360 nm excitation. Moreover, these green luminescent DEG-CDs could be efficiently uptaken by C6 glioma cells and exhibited a low cytotoxicity, suggesting their potentials in bio-imaging applications.     

Highly efficient and environmentally friendly microwave-assisted hydrothermal rapid synthesis of ultralong hydroxyapatite nanowires

Ultralong hydroxyapatite nanowires possess many striking advantages such as high biocompatibility, high flexibility, excellent mechanical properties, high thermal stability, and excellent fire resistance, thus, are promising for applications in various fields. However, the highly efficient, low-cost, and environmentally friendly synthesis of ultralong hydroxyapatite nanowires remains a great challenge. Herein, we report a highly efficient, low-cost, environmentally friendly and energy-saving microwave-assisted hydrothermal strategy for the rapid synthesis of ultralong hydroxyapatite nanowires. This method is based on the green chemistry strategy, using water as the only solvent in the absence of organic solvents. Ultralong hydroxyapatite nanowires with diameters of tens of nanometers and lengths of hundreds of micrometers can be prepared in a short period of time (within 20?min), which significantly shortens the synthetic time by about two orders of magnitude compared with the conventional solvothermal method, showing an ultrahigh efficiency and significant energy saving. Moreover, the as-synthesized ultralong hydroxyapatite nanowires are the ideal raw material for the fabrication of the highly flexible and fire-resistant inorganic paper, which is promising for various applications such as fire-resistant paper documents, and flexible electronic products.     

Toward the synthesis of 6-hydroxyquinoline starting from glycerol via improved microwave-assisted modified Skraup reaction

An efficient and modified Skraup reaction and Bamberger rearrangement in neat water were developed using nitrobenzene and an inexpensive, abundant and environmentally-friendly glycerol under microwave irradiation conditions was furnish regioselectively to the 6-hydroxyquinoline. The target compound was obtained in 77% yield via efficient domino reaction with a “one pot eleven steps”.     

Antibacterial performance of Ag nanoparticles and AgGO nanocomposites prepared via rapid microwave-assisted synthesis method

Silver nanoparticles and silver-graphene oxide nanocomposites were fabricated using a rapid and green microwave irradiation synthesis method. Silver nanoparticles with narrow size distribution were formed under microwave irradiation for both samples. The silver nanoparticles were distributed randomly on the surface of graphene oxide. The Fourier transform infrared and thermogravimetry analysis results showed that the graphene oxide for the AgNP-graphene oxide (AgGO) sample was partially reduced during the in situ synthesis of silver nanoparticles. Both silver nanoparticles and AgGO nanocomposites exhibited stronger antibacterial properties against Gram-negative bacteria (Salmonella typhi and Escherichia coli) than against Gram-positive bacteria (Staphyloccocus aureus and Staphyloccocus epidermidis). The AgGO nanocomposites consisting of approximately 40 wt.% silver can achieve antibacterial performance comparable to that of neat silver nanoparticles.     

重拾“九字诀”,扶绿抬爱总相宜

<正>低碳经济已成国策,亦为全球经济的法则。低碳相望绿色,腐植酸是地球循环的重要物质,在土壤、水体、大气等生态系统中"无处不思绿"2007年11月14日,在北京人民大会堂庆祝"中国腐植酸产业发展五十年"大会上,竹洲老部长对我提出的腐植酸产业"九字诀"发展模式给予了高度评价,亦为全行广泛认同。     

微波辅助合成聚酯树脂动力学研究

研究了微波辅助合成聚酯树脂的酯化反应动力学,通过对比常规反应动力学的动力学参数,分析了微波在聚酯合成中的作用原理。研究发现微波作用仅在酯化阶段作用明显,反应速率有较大提升,而在缩聚酸解过程中并未有影响。因此本研究分别在微波辐射以及传统加热2种方式下,考察了聚酯树脂酯化阶段反应动力学,并获得了2种方式下的反应动力学参数,计算处理得到微波作用下的反应活化能分别为2#:Ea2=227.5 k J/mol,5#:Ea5=42.5 k J/mol;常规加热下反应的活化能为Ea0=2 032.4 k J/mol。结果表明,微波辐射影响了该阶段的反应动力学,提升了反应速率,有微波非热效应存在,但反应平衡常数并未因此产生变化。     

Synthesis of nano-crystalline NiO-YSZ by microwave-assisted combustion synthesis

Nano-crystalline NiO-YSZ composite powders have been successfully prepared by microwave-assisted combustion of a gel derived from an aqueous solution containing ZrO(NO₃)₂·6H₂O ,Y(NO₃)₃·6H₂O, Ni(NO₃)₂·6H₂O and glycine. The as-prepared powders were examined using X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) techniques. It was found that the process took only a few seconds to obtain NiO-YSZ composite powders. The as synthesized composite powder was a homogeneous mixture of YSZ, NiO and Ni phases with crystallite size of 24.2, 33.6 and 25.3 nm respectively.     

微波辅助阳离子瓜尔胶的合成研究

以瓜尔胶为原料,3-氯-2-羟丙基三甲基氯化铵为醚化剂,氢氧化钠为催化剂,异丙醇作为溶剂,利用微波辅助合成了阳离子瓜尔胶。结果表明,在瓜尔胶醚化过程中使用微波辅助,反应时间是传统阳离子瓜尔胶合成方法的1/6,提高了反应效率。最佳反应条件为:溶剂选用85%异丙醇,微波功率300 W,微波辐射时间为30 min,反应温度40℃,醚化剂与瓜尔胶的物质的量比为0.25,碱与瓜尔胶的物质的量比为0.20。产物水溶性很好,可与表面活性剂复配。     

One-step hydrothermal microwave-assisted synthesis of LaFeO3 nanoparticles

Lanthanum orthoferrite (LaFeO₃) powders were synthesized via a highly efficient one-step hydrothermal microwave-assisted synthesis at relatively low temperatures of 240 °C and pressure of 60 bar. The use of microwave irradiation for heating during the synthesis intensifies the LaFeO₃ crystallization process leading to reduced synthesis duration at least 16 times as compared with conventional heating (3 versus 48 h).     

古“瓷“新赋——感受绿色餐瓷的魅力

民以食为天,身为讲究美食的中国人,除了需要享受餐食本身的美味外,还有什么因素能让您食指大动?是蔬果雕花还是浪漫烛光?除了这些增添情趣的因素外,您也一定不会忽略了最佳配角——盛装美味的餐具。     

The rapid synthesis of nanostructured orthorhombic KNbO3 particles by a microwave-assisted hydrothermal method and their characterization

We studied the molar ratio effects of niobium and potassium precursors on the structure and morphology of potassium niobate powders prepared via microwave-assisted hydrothermal synthesis (MaHS). KNbO₃ nanostructures in the form of nanotowers and nanocubes were obtained at reduced synthesis times (30–240 min). The products were characterized via XRD, Raman spectroscopy, SEM, and TEM; band gap calculations used diffuse reflectance data. The results indicate that KNbO₃ nanostructures were obtained with crystallite sizes ranging from 33 to 52 nm. An orthorhombic crystalline structure was formed from the increase of KOH at a molar ratio Nb₂O₅:KOH (1:8 to 1:16 M). The band-gap of 3.1–3.3 eV has potential use in photodegradation applications.     

Acid-treated bentonite-supported Ni catalysts via rapid microwave-assisted drying for nitrobenzene hydrogenation

Acid-treated bentonite-supported Ni catalysts were prepared using a microwave-assisted drying process, characterized and used for the hydrogenation of nitrobenzene to aniline. Microwave-assisted drying of the catalyst reduced the drying time from 3?h with a traditional heating method to 10?min; after drying by microwave irradiation, the acid-treated bentonite-supported Ni catalysts were more stable due to a smaller crystallite size, a higher dispersion of metallic Ni and stronger interactions between Ni and the acid-treated bentonite support than the traditional drying method. Catalytic studies conducted at 300°C with a nitrobenzene liquid hourly space velocity of 3.6?mL?g^?1?h^?1 and a H₂ gas hourly space velocity of 4,800?mL?g^?1?h^?1 indicated that the catalyst prepared using the microwave heating method maintained a nitrobenzene conversion of >99.9% with an aniline selectivity >93% during a 60-h reaction. In addition, the catalyst dried using a traditional method only functioned for 16?h.     

覆膜砂用酚醛树脂微波合成的研究

研究了以草酸为催化剂，覆膜砂用酚醛树脂在微波辐射下树脂合成工艺，并与传统合成树脂的性能进行了综合比较和分析结果表明，微波辐射不仅大大缩短合成反应时间，而且所得树脂固化速度、流动性及覆膜砂强度也得到了显著的改善。     

咪唑盐离子液体的微波合成、表征及性质研究

通过微波辐射,在无溶剂的状态下以N-甲基咪唑为原料合成了4种氯化1-烷基-3-甲基咪唑盐([Bmim]Cl、[Omim]Cl、[C_12mim]Cl、[C_16mim]Cl)离子液体,并测定了离子液体的表面张力和吸水性能.     

Toward a simple,generic, and rapid simulation of the drying of solid foods

Abstract

In order to simulate the drying of foods, calculations based on finite differences, elements, or volumes are extremely time-consuming, particularly when embedded in an optimization procedure. Such models, involving coupled heat and mass transfers and nonlinear properties and boundaries, give rise to slow simulations. This paper proposes a new method concerning the slab, cylindrical, and spherical geometries. This method gives results equivalent to those of the finite volume method but is more rapid by an order of magnitude. The method is based on an optimized 3-compartment model whose parameters are linked to physically meaningful food properties.     

漫谈景德镇柴窑的"柴""窑""火"

所谓"入窑一色,出窑万彩",形容的是陶瓷坯体最后经过柴窑"火"的烧炼后,成为了精美的瓷品.这是一道难过的"坎",这期间陶瓷坯和"马尾松柴"以及窑炉三者都发生化学与物理的变化,演绎出了用什么样的"柴",什么样的"窑",什么样的火温烧出什么样的"瓷"的神秘变化.     

"绿色"清洗之路

石油高价位以及飓风Katrina将对未来一年全球表面活性剂工业产生深远的影响。介绍了全球表面活性剂工业的现状,具体分析了供应链、原油和主原料等因素对表面活性剂产业链的影响。指出了表面活性剂工业的发展趋势。     

响应面法优化微波辅助合成中碳链甘油三酯工艺

以对甲苯磺酸为催化剂,在微波环境下合成辛酸癸酸甘油三酯,并利用响应面法优化辛酸癸酸甘油三酯的合成过程条件。首先,通过单因素灵敏度分析法对催化剂的选择、酸/醇摩尔比、反应温度、微波功率、催化剂用量、反应时间6个因素进行实验考察,确定了酸/醇摩尔比、反应温度、催化剂用量3个关键因素的优化值及取值范围。采用中心组合设计原则对3个关键因素进行实验设计。以产品羟值为响应值,基于响应实验结果,利用响应面法对实验结果进行了方程回归,得到3个关键因素与响应值的二次关联模型。通过方差分析和平行实验,证明该模型准确可用。确定了中碳链甘油三酯（MCTs）最佳合成条件为：酸/醇摩尔比为3.33：1,反应温度为190℃,催化剂用量为甘油质量的4.30%,微波功率为500 W,反应时间为3 h,得到产品羟值为1.12 mg KOH·g^-1,酯化率高达99.7%,与理论预测值基本相符。与传统加热方式对比,微波辅助合成MCT大大缩短了反应时间。测定了精制提纯后MCT产品的各项物化性能指标,均已达到企业标准。通过红外光谱表征和GC/MS进一步表征产物结构和混合物油脂的组成,甘油三酯得率达到95.7%。     

漫说行业词语“炉”、“窑”及其它

陈述了我国玻璃行业在近几十年对玻璃熔制设备的名称产生岐义的来龙去脉。根据汉字的本义和专业英文辞典的对应译文,作者认为玻璃熔制设备用"炉"比用"窑"更为更理。     

Optimization of microwave-assisted synthesis of cyclodextrin nanosponges using response surface methodology

The reaction of polymerization of cyclodextrins with suitable polyfunctional agents leads to highly cross linked porous structures, referred to as cyclodextrin nanosponges. The conventional heating approach for the synthesis of nanosponges can lead to nonuniform reaction conditions caused by sharp thermal gradients in the bulk solution. In this work, we present a facile method for the synthesis of cyclodextrin nanosponges by microwave irradiation with significant reduction in reaction time. Response surface methodology and Box–Behnken design were used for the optimization of the process parameters including microwave power level (A), reaction time (B) and stirring speed (C). Two dependent variables practical yield and particle size were measured as responses. Mathematical equations and response surface plots were used to relate the dependent variables with independent variables. The optimization model predicted a yield of 96.5287 % and particle size of about 152.355 nm with A, B and C levels of 508.22, 83.55 and 1,471.55 respectively. The observed responses of the optimized process were in close agreement with the predicted values. Three confirmation batches of cyclodextrin nanosponges were synthesized under optimized conditions. The Fourier transformed infrared spectra of nanosponges showed a characteristic peak of the carbonate group at around 1,750 cm^?1 which confirms the formation of nanosponges. TGA revealed the stability of obtained nanosponges up to 325 °C. The nanosponges obtained by microwave irradiation exhibited a higher degree of crystallinity. Dimension of the crystal lattice was found to be equal to 0.70 nm. TEM image confirmed the spherical shape and the particle size range of about 153 nm. Compared to conventional heating method, microwave method resulted in four folds reduction in reaction time and provided with particles of homogeneous size distribution and uniform crystallinity.